Construction Of Magnetic Fluorescence Probe Of The Bacterial AHLs Signal Molecule And Its Application

The spoilage of food is mainly caused by the action of microorganisms,and the growth and expression of biological functions of microorganisms are regulated by their quorum sensing system.Among them,N-acyl homoserine lactone(AHLs)is a typical quorum sensing signal molecule in gram-negative bacteria.Therefore,it is of great significance to establish a detection method with high sensitivity and specific recognition for quorum sensing signal molecule AHLs.In this paper,carbon quantum dots were used as fluorescence conversion signals,N-Z-L-HSL was used as template molecule,iron tetroxide coated with silica was used as supporting material,and surface molecular imprinting technology was used to construct AHLs signal molecular magnetic fluorescence probe.Its morphology,structure and magnetic properties were characterized by transmission electron microscopy,infrared spectroscopy(FI-IR),X-ray powder diffraction(XRD),thermogravimetric analysis(TGA)and vibrating sample magnetometer(VSM).The results of adsorption properties showed that the imprinted polymer has good adsorption effect on the target with an adsorption capacity of 4.9 mg/g.The pseudo-second-order kinetics and Freundlich adsorption isotherm model were more suitable for describing the adsorption process.Based on molecularly imprinted magnetic fluorescent probes,a fluorescence detection method for magnetic carbon quantum dots of AHLs signal molecules in a bacterial quorum sensing system was established.In the target concentration range of 0.625-30 ?g/L,the magnetic fluorescent probe showed a good and linear relationship with N-Z-L-HSL and its six analogs.It was used for the actual sample detection.At the addition levels of 5,10,and 20 ?g/L,the recovery rates of the samples were between 83.1 % and 92.68 %,and the relative standard deviations were below 5.09 %.The results showed that this method can meet the needs of AHLs detection in actual samples.The effect of magnetic fluorescent probe on the biofilm of Pseudomonas aeruginosa was studied by crystal violet staining and TTC test.The effects of polymer on biofilm formation under different conditions of polymer addition amount,culture temperature and culture time were investigated.The results showed that the prepared molecularly imprinted polymer had a certain inhibitory effect on the formation of biofilms.With the increase of the amount of polymer added,the amount of bacterial biofilms showed a downward trend.After the addition of more than 15 mg,the amount of the biofilms tended to be gentle;compared with the culture temperature of 25 ? and 30 ?,when the culture temperature is 37 ?,the polymer has the best inhibition effect on the biofilm;within 0-30 h,compared with the control group,the addition of polymer can inhibit the formation of Pseudomonas aeruginosa biofilm.In addition,molecularly imprinted polymers have a certain inhibitory effect on the growth of P.aeruginosa.